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Synthetic, X-ray structural and polymerization studies on isopropyltetramethylcyclopentadienyl derivatives of titanium

1990; Elsevier BV; Volume: 381; Issue: 1 Linguagem: Inglês

10.1016/0022-328x(90)85447-7

1872-8561

Daniel T. Mallin, Marvin D. Rausch, Eric A. Mintz, Arnold L. Rheingold,

Radioactive element chemistry and processing

The reaction of TiCl3(THF)3 with one equivalent of isopropyltetramethylcyclopentadienyllithium in THF followed by oxidation with HCl afforded [η5-(CH3)2CHC5(CH3)4]TiCl3 (1) in 66% yield. Treatment of 1 with C5H5Tl in refluxing benzene gave [η5-(CH3)2CHC5(CH3)4](η5-C5H5)TiCl2 (2) in 95% yield. Reaction of TiCl3(THF)3 with two equivalents of isopropyltetramethylcyclopentadienyllithium in THF followed by oxidation with HCl afforded [η5-(CH3)2CHC5(CH3)4]2TiCl2 (3) in 73% yield. 3 crystallizes in the monoclinic space group C2/c with a 17.032(2), b 8.275(2), c 19.078(4) Å, and β 120.83(1)° (Z = 4). Least-squares refinement leads to a final R (based on F) of 0.038 for 2658 independent reflections. The structure consists of a bent sandwich structure with a CNT-Ti-CNT (CNT = ring centroid) angle of 137.4(1)° and an unusually acute Cl-Ti-Cl bond angle of 88.81(4)°. Ethylene polymerizations by [η5-(CH3)2CHC5(CH3)4](η5-C5-H5)TiCl2/MAO (MAO = methylalumoxane), [η5-(CH3)2CHC5(CH3)4]2TiCl2/MAO, and (η5-C5H5)2TiCl2/MAO are compared at 1.3 atm over the temperature range of 0–50°C.